When samples are brought to the Facility for analysis, please
submit for each vial an Analysis
Request Form. In general, a separate page should be completed for each vial
submitted. In the unusual case of a large number of "identical"
samples (ex. the analysis of two or three specified PCB congeners down
a core), please contact the Facility to determine if a separate page
will be required for each vial.

The DeltaPlus spectrometer is limited to about one order of
magnitude of dynamic range. All compounds of interest should be within
this concentration ratio range. In general, peaks of about 5 to 50ng
per component per injection are about correct, but please consult with
Facility personnel to determine the current operating conditions. A
peak that is too small generally gives an accurate, but imprecise value.
A peak that is too large will saturate the detector and mathematically
results in a completely useless value. Avoid overspiking of internal
standards.

Please make GC screening runs under standard conditions for
each fraction. Measure, do not estimate, the solvent used for dilution.
Make certain that the runs are long enough to get all high boiling compounds
off of the column. Present the entire run in the trace. Normalize the
intensity scale to the largest peak of interest. Few shortcuts result
in real time savings for either the user or the operator; many result
in samples needing to be re-run.

Derivatize and dilute samples to take full advantage of current
injector capabilities. Derivatize small samples in ground glass V vials
using minimal volumes of BSTFA/Pyridine (total volume approximately
equal to volume expected for proper injection) or other reagent mix.
If possible, leave samples in the reagent mix; our current injector
can handle mixed solvents and inject variable volumes. Also, BSTFA/Pyridine
can be injected at much higher temperatures than DCM or hexane, reducing
post-run cooldown time by up to 10 minutes. If your GC traces are presented
as above, and the samples are in known volume, Facility personnel can
determine correct final dilutions and injection volumes and be
responsible for errors in injection amount.

Whenever possible, bring the entire suite of samples for one
compound class (ex. acids vs. alkanes) at a time. This allows for developing
one set of conditions for all samples of a type. This also allows for
best use of instrument time, since runs in one sequence of different
programs are software limited to the length of the longest program.

Consider developing other derivatives/GC column/program options
which would allow alkanes, fatty alcohols, FAMES, etc. to be run un-fractionated.
Runs and columns will probably be longer, but reduced sample handling,
and reduced number of runs will result in significant savings of sample,
time and money.